In recent years, thermal transfer systems have been developed to obtain prints from pictures that have been generated from a camera or scanning device. According to one way of obtaining such prints, an electronic picture is first subjected to color separation by color filters. The respective color-separated images are then converted into electrical signals. These signals are then transmitted to a thermal printer. To obtain the print, a cyan, magenta or yellow dye-donor element is placed face-to-face with a dye receiver element. The two are then inserted between a thermal printing head and a platen roller. A line-type thermal printing head is used to apply heat from the back of the dye-donor sheet. The thermal printing head has many heating elements and is heated up sequentially in response to one of the cyan, magenta or yellow signals. The process is then repeated for the other colors. A color hard copy is thus obtained which corresponds to the original picture viewed on a screen.
Dye receiver elements used in thermal dye transfer generally include a support (transparent or reflective) bearing on one side thereof a dye image-receiving layer, and optionally additional layers, such as a compliant or cushioning layer between the support and the dye receiving layer. The compliant layer provides insulation to keep heat generated by the thermal head at the surface of the print, and also provides close contact between the donor ribbon and receiving sheet which is essential for uniform print quality.
Various approaches have been suggested for providing such a compliant layer. U.S. Pat. No. 5,244,861 (Campbell et al.) describes a composite film comprising a microvoided core layer and at least one substantially void-free thermoplastic skin layer. Such an approach adds an additional manufacturing step of laminating the composite film to the support, and film uniformity can be variable resulting in high waste factors. U.S. Pat. No. 6,372,689 (Kuga et al.) describes the use of a hollow particle layer between the support and dye receiving layer. Such hollow particles layers are frequently coated from aqueous solutions that necessitate a powerful drying stage in the manufacturing process and can reduce productivity. In addition, the hollow particles can result in increased surface roughness in the finished print that reduces surface gloss. It would be advantageous to provide a compliant layer that enables a high gloss print to be obtained. It would also be advantageous if the technology used to provide such a compliant layer also enables a matte-like print to be obtained if a low gloss finish is desired. It would be further advantageous if this low gloss finish can further be enhanced by the incorporation of additives like matte beads in an aqueous subbing layer.
Copending and commonly assigned U.S. Ser. Nos. 12/490,455 and 12/490,464 (both filed Jun. 24, 2009 by Dontula et al.) describe imaging elements having multiple extruded layers included extruded compliant and antistatic subbing layers. The image receiving layer can be extruded or coated out of an organic solvent. Two or more of such layers can be co-extruded if desired along with optional extruded skin layers.
In addition, U.S. Patent Application Publication 2008/0220190 (Majumdar et al.) describes image recording elements comprising a support having thereon an aqueous subbing layer and an extruded dye receiving layer.
U.S. Pat. No. 4,734,396 (Harrison et al.) describes a dye-receiving element having a solvent-coated compression layer between the support and the dye image-receiving layer to reduce image defects. The compression layer has a compression modulus of less than 350×106 Pascals as determined using a tensile testing machine. The compression layer can comprise a variety of polymers including acrylics, modified polyesters, polydienes and polystyrene foam.
Intermediate layers coated out of aqueous solutions are described for image-receiving elements in U.S. Pat. No. 4,837,200 (Kondo et al.).
U.S. Pat. No. 5,407,894 (Hayashi et al.) describes thermal transfer dye image receiving sheets that have thermoplastic resin coatings on a substrate paper base.
Moreover, U.S. Pat. No. 5,821,028 (Maejima et al.) describes cushioning layers containing various elastomeric resins in thermal transfer image receiving materials.
Despite the advances in the art, there remains a need to simplify the construction of thermal dye transfer receiver elements by eliminating antistatic layers between the substrate and image receiving layer. Yet, this advantage is desired without any loss of thermal imaging or increase in image defects.
Copending and commonly assigned U.S. Ser. Nos. 12/581,921 (filed Oct. 20, 2009 by Majumdar, Honan, and Weidner) and 12/490,464 (filed Jun. 24, 2009, by Dontula, Chang, and Thomas) describe thermal dye transfer receiver elements that include an extruded compliant layer and an antistatic layer adhering it to an image receiving layer.
Commercial image transfer elements sold as Kodak® Xtralife® and Xtralife® II include voided compliant layers attached to an image receiving layer. While the voided nature of the compliant layer provides certain advantages, there is a need to provide a less expensive alternative without sacrificing image transfer and image density.